1. Field of the Invention
The present invention relates to a light-emitting diode lamp and in particular to a light-emitting diode lamp adapted to regulate flow of solder in soldering.
2. The Related Art of the Invention
There is known a light-emitting lamp that has a light-emitting diode (to be referred to as LED hereinafter) as a light source. Such light-emitting lamp has an advantage that use of the LED as a light source allows the lamp to have a good lighting performance with a low electrical power consumption, as well as an excellent mounting performance in mounting the lamp to various electronic devices requiring a light source.
Recent progress in miniaturization of an electric device or the like requires further miniaturization of a light-emitting lamp, which raises problems with heat dissipation of heat generated in lighting a LED and a mounting performance of the lamp. In particular, with respect to the mounting performance the miniaturization of the light-emitting lamp results in further reduced mounting areas thereof, which causes the difficulty of securing a sufficient solder-joint strength, as well as an electrical connection in the light-emitting lamp.
In order to solve the above-described problems there exists a light-emitting lamp where a plurality of concave portions are formed in a bottom surface of the light-emitting lamp each of which is sufficient in size to receive a bump made of a ball-shaped solder, and the solder-joint strength in the light-emitting lamp is designed to be secured by the bottom and the side surface of each concave portion as a solder-joint surface (refer to Japanese Unexamined Patent Publication No. 2000-244022).
FIG. 1 is a cross sectional view of a light-emitting diode lamp disclosed in Japanese Unexamined Patent Publication No. 2000-244022. The light-emitting diode lamp 30 is constructed of an insulating substrate 31, and a sheet material 50 adhered to the insulating substrate 31 through an adhesive film 40.
The insulating substrate 31 includes a bore 31A receiving a LED chip 32, and a first and a second plating layer 54 are disposed in a bottom portion of the bore 31A. The LED chip 32 is mounted on the first plating layer 54 and an upper surface electrode of the LED chip 32 is electrically connected through a wire 33 to the second plating layer 54 having a different polarity.
The sheet material 50 is constructed to cover undersurfaces of metallic sheet materials 51, 52, with an insulating resin 53, which also are electrically insulated through a separation portion 53A of the insulating resin 53 from one another. And concave openings for disposing bumps 55 are formed in the undersurface of the sheet material 50 and the metallic materials 51, 52 are covered with the plating layers 54 on which the bumps 55 are located so that the materials 51, 52 are not exposed to the concave openings According to such construction, both the bottom portion and the side surface of each concave portion covered with the plating layer 54 become a joint surface to the solder in performing solder jointing by melting the bumps, thereby to improve solder-joint performance.